GWA studies have dramatically increased the number of variants known for numerous complex diseases. They have been remarkably successful for identifying targets of exploration, often suggesting unforeseen directions for research on disease mechanisms. Especially for those working on diseases for which few if any genetic variants were previously known, GWA studies have provided a true quantum advance for studies of human biology. At the same time, they have established complex genetic diseases to be incontestably complex, caused by many variants, with mostly small effects unsuited to immediate risk prediction and clinical use. These results have understandably triggered a series of reflections on the magnitude of the contributions of GWA studies in general4,124,125,126,127. Clearly, genome-wide association is relatively new, and its full contribution will only become clear as the biological properties of the variants it uncovers are further investigated. Looking forward, the GWA field is now diversifying its emphasis, with attention shifting not only to diverse populations, but also to structural variation, interaction effects, rare sequence variation, and molecular assays of identified variants.
